Safety switch operating mechanism

ABSTRACT

A drive pin is provided with an outer non-circular portion on which two handle halves are fixedly mounted, an outer circular portion pivotally mounted in a side wall of a switch box and in a handle lock-off plate secured to an outer surface of the side wall and having a drive bar for switch blades pivotally mounted thereon adjacent an inner surface of the side wall, an inner noncircular portion on which a first actuating member is fixedly mounted, and an inner circular portion on which a second actuating member is pivotally mounted and which is itself pivotally mounted in a bracket secured to the inner surface of the side wall. A front portion of the handle lock-off plate is outwardly offset from a rear portion by which the plate is secured to the side wall, an offsetting portion is provided with a slot, and an inner one of the handle halves extends through the slot. The side wall is inwardly embossed around the drive pin to provide a recess between the side wall and the handle lock-off plate, and an annular seal is disposed in the recess in engagement with the outer circular portion of the drive pin. A thin plastic washer is disposed on the drive pin between the inner handle half and the handle lock-off plate. The first and second actuating members are connected by a lost-motion connection. The second actuating member is provided with an overcenter spring driving means and with an aperture through which the blade drive bar extends.

United States Patent 11 1 Cox [ 1 SAFETY swrrcn. OPERATING MECHANISM [75] inventor: Russell Cox, Frankfort, Ky.

[73} Assignee: Square D Company, Park Ridge, Ill.

[22] Filed: Feb. 28, 1972 211 App]. No.: 229,896

' [52] US. Cl. 74/97, 200/168 G, 200/50 A [51] Fl6h 21/44 [58] Field of Search 74/97; 200/16 86,

zoo/172A, 50 A, 42

[56] References Cited UNITED STATES PATENTS 3,378,666 4/1968 ,Rys .Q .1 200/168 G 3,339,047 8/1967 Rys et al. '200/50 A 3,222,465 12 1965 Huntress et 211.... 200/168 0 3,317,698 5/1967 Mansfield 200/168 0 Primary Examiner-Charles J. Myhre Assistant Examiner-Wesley S. Ratliff, Jr. Attorney-Harold J. Rathbun et al.

[57] ABSTRACT A drive pin is provided with an outer non-circular portion on which two handle halves are fixedly mounted,

[ Oct. 3t), 1973 an outer circular portion pivotally mounted in a side wall of a switch box and in a handle lock-off plate secured to an outer surface of the side wall and having a drive bar for switch blades pivotally mounted thereon adjacent an inner surface of the side wall, an inner non-circular portion on which a first actuating member is fixedly mounted, and an inner circular portion on which a second actuating member is pivotally mounted and which is itself pivotally mounted in a bracket secured to the inner surface of the side wall. A front portion of the handle lock-off plate is outwardly offset from a rear portion by which the plate is secured to the side wall, an offsetting portion is provided with a slot, and an inner one of the handle halves extends through the slot. The side wall is inwardly embossed around the drive pin to provide a recess between the side wall and the handle lock-off plate, and an annular seal is disposed in the recess in engagement with the outer circular portion of the drive pin. A thin plastic washer is disposed on the drive pin between the inner handle half and the handle lock-off plate. The first and second actuating members are connected by a lost-motion connection. The second actuating member is provided with an over-.center spring driving means and with an aperture through which the blade drive bar extends.

18 Claims, 9 Drawing Figures PATENIEUBBTBO ma 3, 768,321

; sum 10F 2 FIG. 5

PATENTEDHEI 30 ms 3. 768.321

sum 2 or 2 FIG? 4 b r42 SAFETY SWITCH OPERATING MEQHANISM This invention relates generally to operating mechanism for safety switches, and more particularly to an operating mechanism in which the parts are constructed and arranged to provide a better sealing arrangement against leakage of liquid into a box of a safety switch at the projection of a switch blade drive pin through a side wall of the box for the mounting of an exterior operating handle assembly thereon, and to provide a more reliable connection between ,a switch blade drive bar and an actuating member therefor.

An object of the invention is to provide a safety switch operating mechanism having improved sealing means at the projection of a'switch blade drive pin through a side wall of a box and having an improved connection between a switch blade drive bar and an actuating member therefor.

Other objects will appear when the following specification is considered along with the accompanying drawings in which:

FIG. 1 is a fragmentary front view of a safety switch having an operating mechanism constructed in accordance with the invention, a front cover being broken away, certain switch parts being omitted, and the parts of the mechanism being shown in ON position;

FIG. 2 is an enlarged sectional view taken generally along the line 22 of FIGS. 1 and 9, but with certain parts rotated to better show their interrelationship;

FIG. 3 is a perspective view of a drive pin of the mechanism of FIGS. 1 and 2;

' FIG. 4 is an enlarged side view of a seal for the drive P FIG. 5 is a sectional view taken along the line 55 of FIG. 4;

FIG. 6 is a fragmentary perspective view of the operating mechanism of FIGS. 1 and 2;

FIG. 7 is a fragmentary sectional view taken generally along the line 77 of FIG. 1, but including a bandle and lock-off plate of the mechanism in phantom;

FIG. 8 is a fragmentary sectional view similar to FIG.

7, but showing the parts of the mechanism in an OFF side view taken from the right 14b and a right leg 17b pivotally mounted on a drive pin 20 forming a part of the operating mechanism 13. A plurality of switch blades (not shown) are operatively connected to the insulator 18 in the manner disclosed, for example, in FIGS. 13-15 of U.S. Pat. No. 3,339,047, issued Aug. 29, 1967.

The drive pin 20 is best shown in FIGS. 2 and 3 and includes an outer non-circular portion 20a on which an outer handle half 22 and an inner handle half 23 of a handle 24 are fixedly mounted. An outer circular portion 20b of the drive pin is pivotally mounted in the side wall 14a and in a handle lockl-off plate 25 secured to the outer surface of the side wall 14a. The right leg 17b of the drive bar 17 is pivotally mounted on the portion 20b on the inner side of the side wall 14a. A first actuating member 26 is fixedly mounted on an inner noncircular portion 20c of the drive pin 20, and a second actuating member 27 having a lost-motion connection to the actuating member 26 is pivotally mounted on an inner circular portion 20d. The circular portion 20d is pivotally mounted in a bracket 28 secured to the side wall on the inner side thereof, and a push nut 30 on the portion 20d retains the drive pin 20 against outward axial displacement.

The actuating member 26 is provided with a notch 26a (FIGS. 7 and 8) into which a bent tang 27a of the actuating member 27 fits with clearance to provide the above-mentioned lost-motion connection. An overcenter compression spring 32 is operatively connected to the actuating member 27 to provide snap-action opening and closing of the switch blades (not shown). The spring 32 is mounted on a pair of guide members 33 and 34 reciprocally mounted adjacent one end in a slotted leg 35a of a pivotable L-shaped bracket 35 having a leg 35b pivotally mounted on a pin 36 secured in the side wall 14a. Adjacent their other ends the guide members 33 and 34 are outwardly offset to collectively provide a fork carrying a pin 38 trapped in a notch 27b provided in the actuating member 27. At all times one end of the spring 32 bears againstthe leg 35a and the other end bears against a slotted stop collar 39 mounted on the guide members 33 and 34.

Each of the actuating members 26 and 27 is provided with a suitable arcuate aperture into which appropriate fingers extend from opposite ends inside a compression spring 40. The actuating member 26 and thereby the handle 24 are always biased from the actuating member 27 toward ON position of the handle. Mounted on the free end portions of the handle halves 22 and 23 is a hand grip member 42 formed of two halves 42a and 42b secured together by a rivet 44.

Interlock means are provided to prevent movement of the handle 24 to ON position while the cover 15 is open and to prevent opening movement of the cover 15 while the handle 24 is on ON position. A pin 46 is pivotally mounted adjacent opposite ends respectively in the side wall 14a and in the bracket 28. The pin 46 has an enlarged slotted head portion onthe outer side of the side wall 14a, as shown in FIG. 9, and is circular in cross section except for a generally square portion immediately adjacent the inner surface of the side wall 140, as shown in FIGS. 7 and 8. An interlock member 48 is fixedly mounted on the pin 46, being generally U- shaped (FIG. 1) in a mounting portion thereof with an inner leg portion 48a mounted on a circular inner portion of the pin 46 and an outer leg portion 48b mounted on the square portion of the pin 46. A bight portion of the member 48 is provided with an angular extension portion 48c (FIGS. 7 and 8), and the leg portion 48b is provided with an elongated lateral extension 48d having an inwardly bent tang 48e adjacent an outer end. A torsion spring 50 (FIG. 1) on the pin 46 continually biases the member 48 toward the position shown in FIG. 8 from the position shown in FIG. 7. A generally L-shaped bracket 52 (FIGS. 2 and 7) includes a leg portion 520 secured to the inside of the cover 15 and a leg portion 52b cooperable with the tang 4812.

When the cover 15 is open and the handle 24 is in OFF position, the spring 50 biases the interlock member 48 to the position shown in FIG. 8. If an attempt is then made to move the handle 24 to ON position, the

As the cover 15 is closed, the leg portion 52b is first moved inwardly of the tang 48e, and then the cover 15 upon final closing movement engages a cam surface 48f 5 on the outer end of the interlock member 48 and rotates the member 48 to the position of FIG. 7, wherein the tang 48e is aligned with the leg portion 52b and the portion 48c is clear of the notch 27. The cover can then be reopened if the handle 24 is in OFF position, because partial opening of the cover releases the member 48 for movement by the spring 50 back to the position of FIG. 8, wherein the tang 482 does not interfere with the leg portion 52b. With the cover 15 closed, however, the handle 24 can be moved to ON position, the notch 27c clearing the portion 480, and the actuating member 27 then holds the interlock member 48 so that the tang 48e remains in alignment with the leg portion 52b and the cover 15 cannot be opened.

The interlock means can be defeated by a knowledgeable person. When the cover 15 is closed, a screwdriver can be inserted in the slotted head of the pin 46 and turned clockwise as viewed in FIG. 9 to rotate the member 48 clockwise as viewed in FIG. 7 and move the tang 48e out of interfering relationship with the leg portion 52b. The cover 15 can then be opened when the handle 24 is in ON position. When the cover 15 is open, the pin 46 can be rotated clockwise as viewed in FIG. 8 to move the portion 48c out of alignment with the notch 27. The handle 24 can then be moved to ON position when the cover 15 is open.

The actuating member 27 is provided with an aperture 27d through which the right leg 17b of the drive bar 17 extends. With this arrangement, as opposed to an open notch, it is impossible for the actuating member 27 and the drive bar 17 to become operatively disengaged through distortion, loosening of mountings,

abuse of the switch, or any other cause.

The handle lock-off plate 25 includes a rear portion 25a secured to the outer surface of the side wall 14a and a'fron't portion 25b outwardly offset from the rear portion 25a by an offsetting portion 25c having an elongated slot 25d. The mounted end portions of the handle 25b. This construction and arrangement perrnitsbetter sealing at the drive pin 20 than in former switches direction by engagement thereof with the'bracket 28 and in the other direction by engagement thereof with a stop pin 58 mounted adjacent opposite ends respectivelyin the bracket 28 and in the side wall 14a and the rear portion 25a of the handle lock-off plate 25 collectively. An aperture 25e is provided in the front portion 25b of the handle lock-off plate 25 for reception of a padlock hasp-to lock the handle 24 in OFF position.

Various modifications may be made in the structure shown and described without departing from the spirit and scope of the invention.

I claim: t 1. A safety switch operating mechanism comprising a box having a pair of opposite side walls, a bracket mounted in the box, a handle lock-off plate having a rear portion secured to an outer surface of one of the side walls, a front portion outwardly offset from the rear portion, and an offsetting portion connecting the front and rear portions and having an elongated slot therein, a drive pin pivotally mounted adjacent opposite ends respectively in the bracket and in the one side wall and the rear portion of the handle lock-off plate, an inner handle half and an outer handle half each having a mounted end portion disposed outwardly of the rear portion of the handle lock-off plate and mounted on the drive pin, at least one of the handle halves being fixedly mounted on the drive pin for pivoting of the wherein no slotted offsetting portion such as the portion 25c was provided and an inner handle half such as the handle half 23 was disposed entirely on the inner side of the handle lockoff plate. The side wall 14a is inwardly recessed around the drive pin 20 and a seal 54 best shown in FIGS. 4 and 5 is provided around the outer circular portion 20b between the side wall 14a and the rear portion 25a of the handle lock-off plate 25. The seal 54includes a metallic washer portion 54a having an elastic O-ring type seal 54b anchored to its inner periphery. A thin plastic washer 56 is provided on the circular portion 20b between the rear portion 25a of the handle lock-off plate 25 and the mounted end portion of the inner handle half 23.

As can be seen respectively in FIGS. 7 and 8, pivotal movement of the actuating member 27 is limited inone drive pin upon pivotal movement of thehandle halves, the inner handle half extending through the slot in the offsetting portion of the handle lock-off plate to dispose a free end portion thereof on the inner side of the front portion of the handle lock-off plate, a free end portion of the outer handle half being disposed on the outer side of the front portion of the handle lock-off plate, a hand grip member mounted on the free end portions of the handle halves, a first actuating member fixedly mounted on the drive pin for pivotal movement therewith, a second actuating member pivotally mounted on the drive pin, operatively connected to the first actuating member by a lost-motion connection, and having an aperture'therethrough, an over-center spring operatively connected to the second actuating member, anda generally U-shaped switch blade drive bar including a'leg portion extending through-the aperture inthe second actuating member and having a free end portion pivotally mounted on the drive pin.

2. An operating mechanism as claimed in claim I wherein the drive'pin has an inner circular portion pivotally mounted in the bracket, an outer circular portion pivotally mounted in the one side wall and in the rear portion of the handle lock-off plate, an inner noncircular portion between the inner and outer circular portions, and an outer non-circular portion outwardly of the outer circular portion, the handle halves are fixedly mounted on the outer non-circular portion, the

first actuating member is fixedly mounted on the inner non-circular. portion, the second actuating member is pivotally mounted on the inner circular portion, and the leg portion of the switch blade drive bar is pivotally mounted on the outer circular portion.

7 3. An operating mechanism as claimed in claim I wherein the one side wall and the rear portion of the handle lock-off plate collectively are contoured to provide a recess therebetween extending around the drive pin and an elastic O-ring type seal is disposed in the recess and extends around the drive pin.

4. An operating mechanism as claimed in claim 1 wherein also the other of the handle halves is fixedly mounted on the drive pin.

5. An operating mechanism as claimed in claim wherein the switch blade drive bar includes a leg portion pivotally mounted on a pin secured to the other of the side walls.

6. An operating mechanism as claimed in claim 1 including a plastic washer mounted on the drive pin between the rear portion of the handle lock-off plate and the mounted end portion of the inner handle half.

7. An operating mechanism as claimed in claim 1 wherein the bracket is mounted on the one side wall.

8. A safety switch operating mechanism comprising a box having a pair of opposite side walls, a bracket mounted in the box, a handle lock-off plate having a rear portion secured to an outer surface of one of the side walls, a front portion outwardly offset from the rear portion, and an offsetting portion connecting the front and rear portions and having an elongated slot therein, a drive pin pivotally mounted adjacent opposite ends respectively in the bracket and in the one side wall and the rear portion of the handle lock-off plate, an inner handle half and an outer handle half each having a mounted end portion disposed outwardly of the rear portion of' the handle lock-off plate and mounted on the drive pin, at least one of the handle halves being fixedly mounted on the drive pin for pivoting of the drive pin upon pivotal movement of the handle halves, the inner handle half extending through the slot in the offsetting portion of the handle lock-off plate to dispose a free end portion thereof on the inner side of the front portion of the handle lock-off plate, a free end portion of the outer handle half being disposed on the outer side of the front portion of the handle lock-off plate, a hand grip member mounted on the free end portions of the handle halves, a first actuating member fixedly mounted on the drive pin for pivotal movement therewith, a second actuating member pivotally mounted on the drive pin and operatively connected to the first actuating member by a lost-motion connection, an overcenter spring operatively connected to the second actuating member, and a pivotally mounted generally U-shaped switch blade drive bar operatively connected to the second actuating member for pivoting thereby.

9. An operating mechanism as claimed in claim 8 wherein the one side wall and the rear portion of the handle lock-off plate collectively are contoured to provide a recess therebetweenextending around the drive pin and an elastic 0-ring type seal is disposed in the recess and extends around the drive pin.

10. An operating mechanism as claimed in claim 8 wherein also the other of the handle halves is fixedly mounted on the drive pin.

11. An operating mechanism as claimed in claim 8 wherein the switch blade drive bar includes a leg portion pivotally mounted on the drive pin and an opposite leg portion pivotally mounted on a pin secured to the other of the side walls.

12. An operating mechanism as claimed in claim 8 including a plastic washer mounted on the drive pin between the rear portion of the handle lock-off plate and the mounted end portion of the inner handle half.

l3. An operating mechanism as claimed in claim 8 wherein the bracket is mounted on the one side wall.

14. A safety switch operating mechanism comprising a box having a pair of opposite side walls, a bracket mounted in the box, a drive pin mounted adjacent opposite ends respectively in the bracket and in one of the side walls, a handle fixedly mounted on the drive pin on I the outer side of the one side wall for pivoting of the drive pin upon pivotal movement of the handle, a first actuating member fixedly mounted on the drive pin for pivotal movement therewith, a second actuating member pivotally mounted on the drive pin, operatively connected to the first actuating member by a lostmotion connection, and having an aperture therethrough, an over-center spring operatively connected to the second actuating member, and a generally U- shaped switch blade drive bar including a leg portion extending through the aperture in the second actuating member and having a free end portion pivotally mounted on the drive pin.

15 A safety switch as claimed in claim 14 wherein the switch blade drive bar includes a leg portion pivotally mounted on a pin secured to the other of the side walls.

1 6. An operating mechanism as claimed in claim 14 wherein the bracket is mounted on the one side wall.

17. A safety switch operating mechanism as claimed in claim 8 wherein the drive pin has an inner circular portion pivotally mounted in the bracket, an outer circular portion pivotally mounted in the one side wall and in the rear portion of the handle lock-off plate, an inner non-circular portion between the inner and outer circular portions, and an outer non-circular portion outwardly of the outer circular portion, the handle halves are fixedly mounted on the outer non-circular portion, the first actuating member is fixedly mounted on the inner non-circular portion, the second actuating member is pivotally mounted on the inner circular portion, and the switch blade drive bar includes a leg portion pivotally mounted on the outer circular portion.

18. A safety switch operating mechanism as claimed in claim 14 wherein the drive pin has an inner circular portion pivotally mounted in the bracket, an outer circular portion pivotally mounted in the one side wall, an inner non-circular portion between the inner and outer circular portions, and an outer noncircular portion outwardly of the outer circular portion, the handle is fixedly mounted on the outer non-circular portion, the first actuating member is fixedly mounted on the inner non-circular portion, the second actuating member is pivotally mountedon the inner circular portion, and

the free end portion of the leg portion of the switch blade drive bar is pivotally mounted on the outer circular portion. 

1. A safety switch operating mechanism comprising a box having a pair of opposite side walls, a bracket mounted in the box, a handle lock-off plate having a rear portion secured to an outer surface of one of the side walls, a front portion outwardly offset from the rear portion, and an offsetting portion connecting the front and rear portions and having an elongated slot therein, a drive pin pivotally mounted adjacent opposite ends respectively in the bracket and in the one side wall and the rear portion of the handle lock-off plate, an inner handle half and an outer handle half each having a mounted end portion disposed outwardly of the rear portion of the handle lock-off plate and mounted on the drive pin, at least one of the handle halves being fixedly mounted on the drive pin for pivoting of the drive pin upon pivotal movement of the handle halves, the inner handle half extending through the slot in the offsetting portion of the handle lock-off plate to dispose a free end portion thereof on the inner side of the front portion of the handle lock-off plate, a free end portion of the outer handle half being disposed on the outer side of the front portion of the handle lock-off plate, a hand grip member mounted on the free end portions of the handle halves, a first actuating member fixedly mounted on the drive pin for pivotal movement therewith, a second actuating member pivotally mounted on the drive pin, operatively connected to the first actuating member by a lost-motion connection, and having an aperture therethrough, an over-center spring operatively connected to the second actuating member, and a generally U-shaped switch blade drive bar including a leg portion extending through the aperture in the second actuating member and having a free end portion pivotally mounted on the drive pin.
 2. An operating mechanism as claimed in claim 1 wherein the drive pin has an inner circular portion pivotally mounted in the bracket, an outer circular portion pivotally mounted in the one side wall and in the rear portion of the handle lock-off plate, an inner non-circular portion between the inner and outer circular portions, and an outer non-circular portion outwardly of the outer circular portion, the handle halves are fixedly mounted on the outer non-circular portion, the first actuating member is fixedly mounted on the inner non-circular portion, the second actuating member is pivotally mounted on the inner circular portion, and the leg portion of the switch blade drive bar is pivotally mounted on the outer circular portion.
 3. An operating mechanism as claimed in claim 1 wherein the one side wall and the rear portion of the handle lock-off plate collectively are contoured to provide a recess therebetween extending around the drive pin and an elastic O-ring type seal is disposed in the recess and extends around the drive pin.
 4. An operating mechanism as claimed in claim 1 wherein also the other of the handle halves is fixedly mounted on the drive pin.
 5. An operating mechanism as claimed in claim 1 wherein the switch blade drive bar includes a leg portion pivotally mounted on a pin secured to the other of the side walls.
 6. An operating mechanism as claimed in claim 1 including a plastic washer mounted on the drive pin between the rear portion of the handle lock-off plate and the mounted end portion of the inner handle half.
 7. An operating mechanism as claimed in claim 1 wherein the bracket is mounted on the one side wall.
 8. A safety switch operating mechanism comprising a box having a pair of opposite side walls, a bracket mounted in the box, a handle lock-off plate having a rear portion secured to an outer surface of one of the side walls, a front portion outwardly offset from the rear portion, and an offsetting portion connecting the front and rear portions and having an elongated slot therein, a drive pin pivotally mounted adjacent opposite ends respectively in the bracket and in the one side wall and the rear portion of the handle lock-off plate, an inner handle half and an outer handle half each having a mounted end portion disposed outwardly of the rear portion of the handle lock-off plate and mounted on the drive pin, at least one of the handle halves being fixedly mounted on the drive pin for pivoting of the drive pin upon pivotal movement of the handle halves, the inner handle half extending through the slot in the offsetting portion of the handle lock-off plate to dispose a free end portion thereof on the inner side of the front portion of the handle lock-off plate, a free end portion of the outer handle half being disposed on the outer side of the front portion of the handle lock-off plate, a hand grip member mounted on the free end portions of the handle halves, a first actuating member fixedly mounted on the drive pin for pivotal movement therewith, a second actuating member pivotally mounted on the drive pin and operatively connected to the first actuating member by a lost-motion connection, an overcenter spring operatively connected to the second actuating member, and a pivotally mounted generally U-shaped switch blade drive bar operatively connected to the second actuating member for pivoting thereby.
 9. An operating mechanism as claimed in claim 8 wherein the one side wall and the rear portion of the handle lock-off plate collectively are contoured to provide a recess therebetween extending around the drive pin and an elastic O-ring type seal is disposed in the recess and extends around the drive pin.
 10. An operating mechanism as claimed in claim 8 wherein also the other of the handle halves is fixedly mounted on the drive pin.
 11. An operating mechanism as claimed in claim 8 wherein the switch blade drive bar includes a leg portion pivotally mounted on the drive pin and an opposite leg portion pivotally mounted on a pin secured to the other of the side walls.
 12. An operating mechanism as claimed in claim 8 including a plastic washer mounted on the drive pin between the rear portion of the handle lock-off plate and the mounted end portion of the inner handle half.
 13. An operating mechanism as claimed in claim 8 wherein the bracket is mounted on the one side wall.
 14. A safety switch operating mechanism comprising a box having a pair of opposite side walls, a bracket mounted in the box, a drive pin mounted adjacent opposite ends respectively in the bracket and in one of the side walls, a handle fixedly mounted on the drive pin on the outer side of the one side wall for pivoting of the drive pin upon pivotal movement of the handle, a first actuating member fixedly mounted on the drive pin for pivotal movement therEwith, a second actuating member pivotally mounted on the drive pin, operatively connected to the first actuating member by a lost-motion connection, and having an aperture therethrough, an over-center spring operatively connected to the second actuating member, and a generally U-shaped switch blade drive bar including a leg portion extending through the aperture in the second actuating member and having a free end portion pivotally mounted on the drive pin.
 15. A safety switch as claimed in claim 14 wherein the switch blade drive bar includes a leg portion pivotally mounted on a pin secured to the other of the side walls.
 16. An operating mechanism as claimed in claim 14 wherein the bracket is mounted on the one side wall.
 17. A safety switch operating mechanism as claimed in claim 8 wherein the drive pin has an inner circular portion pivotally mounted in the bracket, an outer circular portion pivotally mounted in the one side wall and in the rear portion of the handle lock-off plate, an inner non-circular portion between the inner and outer circular portions, and an outer non-circular portion outwardly of the outer circular portion, the handle halves are fixedly mounted on the outer non-circular portion, the first actuating member is fixedly mounted on the inner non-circular portion, the second actuating member is pivotally mounted on the inner circular portion, and the switch blade drive bar includes a leg portion pivotally mounted on the outer circular portion.
 18. A safety switch operating mechanism as claimed in claim 14 wherein the drive pin has an inner circular portion pivotally mounted in the bracket, an outer circular portion pivotally mounted in the one side wall, an inner non-circular portion between the inner and outer circular portions, and an outer noncircular portion outwardly of the outer circular portion, the handle is fixedly mounted on the outer non-circular portion, the first actuating member is fixedly mounted on the inner non-circular portion, the second actuating member is pivotally mounted on the inner circular portion, and the free end portion of the leg portion of the switch blade drive bar is pivotally mounted on the outer circular portion. 